JPH0641591B2 - Sliding contact grease - Google Patents

Description

TECHNICAL FIELD The present invention relates to a grease for sliding contacts. The grease is a sliding switch in which a movable contact slides on a sliding surface of a stator having a fixed contact attached to a resin-based insulator to open and close the switch,
In particular, it is particularly useful as a grease for sliding contacts that generates an electric arc when the switch is opened / closed, but is not limited to this.

2. Description of the Related Art Conventionally, this type of sliding switch has the following problems due to deterioration of the sliding contact grease over time. That is, (i) grease and lubricating components disappear on the contact surface, oil on the contact surface runs out, oxidation on the sliding surface occurs, and foreign matter is formed on the contact surface, increasing the voltage drop. Abrasion powder adheres to the insulator, causing insulation deterioration, (iii) Arc of grease carbide residue due to arc adheres to the insulator, leading to deterioration of the leading edge, and (iv) Grease with high viscosity at low temperature contacts There is a case in which the contact surface becomes a leading edge at low temperature by adhering to the surface, or (V) oil penetrates into the insulator to lower the critical stress and cause cracks or the like in the insulator.

For this reason, the development of grease having the following characteristics (a) to (e) is required in this field: (a) High durability with no foreign matter generated on the contact surface under electric arc The voltage drop is small, (b) the lubricity is not lost even under high temperature such as electric arc, and the wear is not increased. (C) The carbide residue is not generated even when heated by the electric arc.

(d) Wide range of temperature from low temperature to high temperature (-30 ℃ to 150 ℃)
(E) Plastic (PC, ABS, PMMA, etc.) that can be used at (° C) is not put on the surface.

However, no sliding contact grease having such characteristics has been proposed. For example, a grease containing a chain hydrocarbon as a base oil and a lithium salt of a fatty acid as a thickener is excellent in terms of (a) and (e), but produces a carbide residue under an electric arc. . In addition, the viscosity of the grease blended with polybutene satisfying the characteristics of (c) as a base oil increases at low temperature. A grease containing a polyhydric alcohol addition polymerization oligomer of alkylene oxide as a base oil and a lithium salt of a fatty acid as a thickener may be used in a DC circuit because of a negative base oil, and contacts may be consumed. Further, it is considered that the abrasion of the abrasion powder, which is negatively charged by friction, cannot be suppressed, and the lubricity in such a case is deteriorated. Furthermore, silicone grease has a problem in point (a).

DISCLOSURE OF THE INVENTION In view of such circumstances, the present invention has been made to provide a grease for sliding contacts having the characteristics (a) to (e) described above.

Means for Solving the Problems That is, an alkylene oxide-polyhydric alcohol addition polymerization oligomer and a chain hydrocarbon oligomer are used in a molar ratio of 1:
Sliding containing 5 to 30 parts by weight of a lithium salt of a higher fatty acid and 0.5 to 10 parts by weight of a clay mineral containing a quaternary ammonium salt having an affinity for organic substances, based on 100 parts by weight of a base oil contained in a ratio of 0.2 to 1.5. Regarding contact grease.

The alkylene oxide-polyhydric alcohol addition polymerization oligomer used in the present invention is one or more compounds selected from alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide, and the like, and polyhydric alcohols such as ethylene glycol. A lipophilic oligomer obtained by addition-polymerizing a polyhydric alcohol selected from propylene glycol and the like by a conventional method and having a molecular weight of usually 300.
˜4000, preferably 1000-2000.

Particularly suitable addition-polymerization oligomers of this type have the following formula: [R ₁ O- (PO) n (BO) m] lR (wherein R ₁ has a carbon number of 1 to 1 which may have a branched chain).
18 represents a hydroxyalkyl group, R represents a hydrogen atom or a hydrocarbon residue having 1 to 18 carbon atoms which may have a branched chain, and PO and BO represent a propylene oxide residue and a butylene oxide residue, respectively. Shows,
n is an integer of 1 to 2 to several tens, m is an integer of 0, 1 or 2, and l is an integer of 1 or more). The molecular weight of the oligomer is usually 30
It is 0 to 3,000, preferably 1,000 to 2,000.

As the chain hydrocarbon oligomer used in the present invention, refined paraffinic mineral oil, α-olefin polymerized oil, ethylene
Examples of the α-olefin polymerized oil include the oligomers, and the molecular weight of these oligomers is usually 400 to 3000, preferably 500 to 1500.

Particularly suitable oligomers of this type have from 6 to 6 carbon atoms.
12 hydrogenated α-olefin oligomers or ethylene / α-olefin oligomers having an ethylene content of 30 to 70% by weight are exemplified.

The base oil of the sliding contact grease according to the present invention comprises the above alkylene oxide-polyhydric alcohol addition polymerization oligomer and a chain hydrocarbon oligomer having a molecular weight of 1/2 to 1/3 of the molecular weight of the base oil in a molar ratio of 1 : Included in the ratio of 0.2 to 1.5,
If the addition amount of the addition polymerization oligomer is more than the above range, the polarity of the base oil is affected, and there is a concern that the contact will be consumed in the DC circuit. On the other hand, if the amount is too small, carbonization of the chain hydrocarbon oligomer due to arc heat when the switch is opened and closed begins to stand out.

The lithium salt of higher fatty acid is most preferably lithium stearate, lithium 12-hydroxystearate and a mixed soap of lithium stearate and lithium 12-hydroxystearate, the amount of which is 100 parts by weight of the above base oil. If the amount is 5 to 30 parts by weight and the amount is 5 parts by weight or less, the contact and the insulator will be consumed much,
On the other hand, if the amount is 30 parts by weight or more, the applicability of grease is deteriorated, which is not preferable.

Examples of the quaternary ammonium salt-containing clay mineral having affinity for organic substances include dimethyl octadecyl ammonium montmorillonite and dimethyl pentyl octadecyl ammonium hectorite. The amount of the clay mineral compounded is 0.
When the amount is less than 5 parts by weight to less than 10 parts by weight and less than 0.5 parts by weight, it is difficult to obtain the intended effect of the present invention, and when it is 10 parts by weight or more, the grease is provided with conductivity, which is preferable. Absent.

If desired, the grease for sliding contacts according to the present invention may be appropriately mixed with various conventional additives, polymers, thickeners and the like to adjust the viscosity index and oil separation degree of the grease.

The grease according to the present invention is suitable for application to the contact sliding surface of the sliding switch as shown in FIG. 1, for example. That is, in the sliding switch, the fixed contact (2) is embedded in the resin-based insulator (1), and the air gap (3) is provided between the fixed contact (2) and the insulator (1). The contact part (4a) of the movable contact (4) slides on the flat plate stator to make contact with and separate from the fixed contact surface (2a) to open / close the switch. Cut a few amps ~
A switch having a structure in which a current of several tens of amperes is opened and closed to generate an electric arc, wherein the grease (5) according to the present invention comprises a surface (2a) of the insulator (1) and a surface (2a) of the fixed contact (2). ) To a predetermined thickness.

Hereinafter, the present invention will be further described with reference to examples.

Examples 1 to 3 Table 1 shows the properties of the sliding contact grease 1 (Example 1), 2 (Example 2) and 3 (Example 3) according to the present invention prepared according to the formulation of Table-1. .

Comparative Examples 1 to 4 Sliding contact greases 1 '(Comparative Example 1), 2' (Comparative Example 2), 3 '(Comparative Example 3) and 4' (Comparative Example 4) prepared according to the formulation of Table-1. The properties of are shown in Table-1.

Grease performance test Greases 1-3 and 1'-prepared as described above
The following tests were conducted to evaluate the performance of 4 '.

2 and 3 similar to the sliding switch shown in FIG.
The sliding switch for experiment shown in the figure was created. The stator (10) shown in FIG. 2 has a fixed contact (12) and a fixed contact (13) embedded at a 90 degree interval in the center of a resin insulator (11), and a sliding portion of a movable contact (14). Air gaps (15) are provided on both sides of the fixed contact (13) which hits against. As shown in FIG. 3, the stator (10) is fixed to a rotary shaft (17) of a rotary motor (16), while a pair of movable contacts (14) and (19) fixed to a base (18). Is placed above the stator (10) so that the contact surface (19a) of the movable contact (19) is always in contact with the fixed contact (12) at the center of the stator (10), and the contact part of the movable contact (14) is (14a) is brought into contact with and separated from the fixed contact (13), so that the switch is opened and closed.

A mineral-blended nylon 66 resin molded body or a glass fiber-blended polyester resin molded body was used as the resin insulator (11), and copper contacts were used as the contacts (12) to (14) and (19).

Add each grease prepared as above to the stator (10).
Of resin insulation (11) and fixed contacts (12) and (13)
Was applied to the surface of (amount of application: 10 mg / cm ² ).

The test conditions are DC24.5V, 120W, switching speed 1cm / to generate sufficient electric arc when switching the switch.
The durability performance (a ′) to (e ′) of the switch was evaluated by conducting a durability test for 50,000 revolutions or more under the condition of sec, and the results are shown in Table 1.

In this case, the durability performances (a ')-(e') correspond to the desired properties (a)-(e) of the grease described above, and are tested in tests I and II
Is a nylon 66 resin containing minerals as an insulator
This is an evaluation when [(kaolin / talc) (20/20%) blended nylon 66] and glass fiber 20% blended unsaturated polyester resin are used.

The evaluation criteria for durability performances (a ')-(e') are as follows.
(a ') and (c') were measured at 4 points respectively.

(a '); A when the voltage drop is 50 mV or less, and B when it is more than 50 mV.

(b '); A is used when the contact wear amount is 2.5 mg or less, and B is used when the contact wear amount is more than 2.5 mg.

(c '); Insulation resistance at 3mm from air gap is 10M
The case of Ω or more is A, and the case of less than B is B.

(d '); A is the case where the starting torque and the rotating torque at -30 ° C are 2000 gcm or less and 1000 gcm or less, respectively, and B is the case above these.

(e ′); A at 80 ° C. when PC, PMMA and ABS are not put (when there is no decrease in critical stress),
The case where these are removed is designated as B.

Furthermore, for some samples, 3mm from the number of durability tests and voltage drop or air gap in the above durability test
The relationship with the insulation resistance at the distant points is shown in FIGS. These maximum values were measured at 4 points of the test sample shown in Fig. 2 (in any case, kaolin / talc as resin insulator) (20/20%) blended nylon 66
It was used). That is, FIGS. 4 and 5 relate to grease 1, FIGS. 6 and 7 relate to grease 2 ', and FIGS. 8 and 9 relate to grease 3'.

Effects of the Invention Chain hydrocarbon oligomer or alkylene oxide-
When the polyhydric alcohol addition polymerization oligomer is used alone as a base oil or as the results of Comparative Examples 1 to 3 show,
Although no grease for sliding contacts having the above desirable characteristics (a) to (e) can be obtained, when the both are used together as a base oil in a predetermined ratio, the results of Examples 1 to 3 show. The characteristics
A grease for sliding contacts having the functions (a) to (e) can be obtained.

For example, when polyoxypropylene glycol monoether is used alone as the base oil, it seems that the insulator material used is also related, but contact wear and wear are significant, and the insulator near the arc gap when the current is interrupted Copper contact wear powder agglomerates and adheres to the surface, causing insulation deterioration (see Fig. 7). Also, when ethylene / α-olefin polymerized oil is used alone, grease carbonization is remarkable and the arc during current interruption Not only a large amount of carbide residue but also copper contact wear powder adheres to the sliding surface of the insulator near the gap, which causes remarkable insulation deterioration and contact wear (see Fig. 9), but polyoxypropylene glycol is used as the base oil. When monoether and ethylene / α-olefin polymerized oil are mixed in a prescribed ratio, carbonization and disappearance of grease due to arc heat are small even if current switching is repeated. Not less generation amount of adhered contact abrasion powder does not result in increased and deterioration of insulation voltage drop
(See Figures 4 and 5).

Therefore, the use of the grease according to the present invention greatly improves the reliability and durability of the sliding switch.

The grease according to the present invention can be generally used as a contact grease for sliding switches, but is particularly suitable as a sliding contact grease for vehicles and the like.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an embodiment of a sliding switch having a contact sliding surface on which the grease for sliding contacts according to the present invention can be preferably used. FIG. 2 is a plan view of the sliding switch stator used in the grease durability test. FIG. 3 is a schematic cross-sectional view passing through the main part of FIG. 4 and 5 show the relationship between the number of times of durability and the voltage drop in the durability test using grease 2, and the relationship between the number of times of durability and the insulation resistance, respectively. 6 and 7 show the relationship between the number of times of durability and the voltage drop and the relationship between the number of times of durability and the insulation resistance in the durability test using grease 2 ', respectively. FIG. 8 and FIG. 9 show the relationship between the durability count and the voltage drop and the relationship between the durability count and the insulation resistance in the durability test using grease 3'and grease 4 ', respectively. (1) and (11) are resin insulators, (2), (12) and (13) are fixed contacts, (3) and (15) are air gaps, (4),
(14) and (19) are movable contacts, (5) is grease for sliding contacts, (10) is a stator, and (16) is a motor.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C10M 107: 10 117: 02 113: 10 115: 08) C10N 10:02 40:14 50:10 ( 72) Inventor Kikuo Hosaki 1-16-5 Nishi-Kamata, Ota-ku, Tokyo (56) Reference JP-A-59-142293 (JP, A) JP-A-48-100654 (JP, A) JP-A-1-152197 (JP, A)

Claims (3)

[Claims] 1. A lithium salt of a higher fatty acid in an amount of 5 to 30 parts by weight per 100 parts by weight of a base oil containing an alkylene oxide-polyhydric alcohol addition polymerization oligomer and a chain hydrocarbon oligomer in a molar ratio of 1: 0.2 to 1.5. And organic matter-friendly quaternary ammonium salt-containing clay mineral 0.5 part by weight-
Sliding contact grease containing less than 10 parts by weight. 2. An alkylene oxide-polyhydric alcohol addition polymerization oligomer has the following formula: [R ₁ O- (PO) n (BO) m] lR (wherein R is the number of carbon atoms which may have a branched chain). 1 to
18 represents a hydroxyalkyl group, R represents a hydrogen atom or a hydrocarbon residue having 1 to 18 carbon atoms which may have a branched chain, and PO and BO represent a propylene oxide residue and a butylene oxide residue, respectively. Shows,
n is a number of 1 to 40, m is an integer of 0, 1, 2 and l is an integer of 1 or more) The grease according to claim 1, which is a polyoxyalkylene glycol ether. 3. The chain hydrocarbon oligomer is a refined paraffinic mineral oil, an α-olefin polymerized oil or an ethylene / α-olefin polymerized oil whose molecular weight is 1/2 of the molecular weight of the polyoxyalkylene glycol ether shown in the above item 2. ~ 1/3
The grease according to item 1, which is